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Extrapolation in the Context of Criteria Setting and Risk Assessment
Published in Keith R. Solomon, Theo C.M. Brock, Dick de Zwart, Scott D. Dyer, Leo Posthuma, Sean M. Richards, Hans Sanderson, Paul K. Sibley, Paul J. van den Brink, Extrapolation Practice for Ecotoxicological Effect Characterization of Chemicals, 2008
Keith R. Solomon, Theo C. M. Brock, Dick de Zwart, Scott D. Dyer, Leo Posthuma, Sean M. Richards, Hans Sanderson, Paul K. Sibley, Paul J. van den Brink
The ecological threshold principle presupposes that the environment can absorb and tolerate a certain amount of stress. An approach in line with the ecological threshold principle is to consider a certain concentration of a substance acceptable if the sensitive structural or functional endpoints of the community are not, or are only briefly, impacted. A permissible concentration in line with the ecological threshold principle can be based on the no-observed-effect concentration (NOEC, or effect class 1; see Table 1.3) or the lowest-observed-effect concentration (LOEC, or effect class 2; see Table 1.3) of the most sensitive measurement endpoint as assessed by an adequately performed microcosm or mesocosm experiment. This threshold concentration derived from model aquatic ecosystem experiments may also guarantee that no adverse indirect effects such as algal blooms due to the direct toxic effects on grazing microcrustaceans will occur. Effect classes that can be used to summarize observed effects in aquatic microcosm or mesocosm studies are described in the European Union’s “Guidance Document on Aquatic Ecotoxicology” (European Commission 2002; after Brock et al. 2000a, 2000b). In Europe, these effect classes (Table 1.3) are used to evaluate semifield tests submitted for the registration of pesticides.
Post-mineral Excavation Sites as Novel Ecosystems and Examples of Socio-environmental Resilience
Published in Artur Dyczko, Andrzej M. Jagodziński, Gabriela Woźniak, Green Scenarios: Mining Industry Responses to Environmental Challenges of the Anthropocene Epoch, 2022
Gabriela Woźniak, Andrzej M. Jagodziński
Many discussions have focused on the definition of novelty. As a result, Morse et al. (2014) presented some concepts of the description. Novel Ecosystems are a unique assemblage of environmental conditions and biota set up due to human (human agency) alteration. The alteration must be sufficient to cross an ecological threshold that moves and maintains a new ecosystem trajectory and prevents its return to a historical, previous course even without additional human disturbance. Furthermore, the resulting Novel Ecosystem must be self-sustaining in ecosystem functioning, including best-adapted species composition, biogeochemistry, feedback relationships, structure, processes, ecosystem functioning and, consequently, ecosystem services.
Space Situational Awareness & Space Traffic Management
Published in M. Madi, O. Sokolova, Space Debris Peril: Pathways to Opportunities, 2020
Such a cycle is referred to as an “ecological threshold,” a point at which a relatively small change or disturbance in external conditions can cause a rapid, exponential change in an ecosystem. In this case, that ecosystem is space. Once the ecological threshold is surpassed, the ecosystem may no longer be able to return to its previous state by means of its inherent resilience (e.g., in space, the ability of drag, gravitational resonances, solar radiation pressure, and other natural forces to “self-cleanse” and remove debris from orbit). Under these conditions, the Earth’s orbital environment would be irreparably harmed.
Mechanisms, monitoring and modeling of shrub encroachment into grassland: a review
Published in International Journal of Digital Earth, 2019
Xin Cao, Yu Liu, Xihong Cui, Jin Chen, Xuehong Chen
Shrub encroachment into grassland indicates a shift from the stable landscape state dominated by grass to another state dominated by shrubs (Anderies, Janssen, and Walker 2002; van Langevelde et al. 2003; Okin, D’Odorico, and Archer 2009). The shrub encroachment process can be observed through several demographic changes (D’Odorico, Okin, and Bestelmeyer 2012). Thus, researchers have divided this process into stages or phases. Xiong, Han, and Bao (2005) proposed three states of the shrub encroachment process based on the steady states of an ecosystem. State 1 or pristine grassland is identified as potential sandy desertification. It is dominated by perennial gramineous grasses, and the ecological function of shrub patches is weaker than the grass matrix. The main grass species are native high gramineous grasses inside and outside shrub patches. State 2 or thicketization grassland is identified as light sandy desertification. It is dominated by shrub patches that consist of shrubs and understory grasses. The main grass species are native high gramineous grasses inside shrub patches and small gramineous grasses or weed outside shrub patches. The ecological function of shrub patches is enhanced in the ecosystem during this state. State 3 or dune shrubland is characterized by heavy sandy desertification. Coppice dunes or nebkhas develop only on sandy soil, thereby indicating severe grassland degradation, soil erosion, and desertification. No continuous grass layer exists within shrub patches, and the basic ecological function of the ecosystem tends to disappear. The shift between states relies on ecological thresholds. The crossing of an ecological threshold indicates changes in the original ecosystem structure and the loss of the corresponding ecological functions, which suggests the overall degradation of the ecosystem (Xiong and Han 2005). D’Odorico, Okin, and Bestelmeyer (2012) divided the shrub encroachment process into four stages: (I) pure grassland with nearly no shrub, (II) grassland with limited shrub cover, (III) shrubland where most grass cover is absent and shrubs have increased in size and density, and (IV) shrub duneland. Stages II–IV can correspond to Stages 1–3 of Xiong, Han, and Bao (2005). Figure 1 shows the stages of Caragana microphylla Lam. encroachment in a steppe in Inner Mongolia, China based on the four stages proposed by D’Odorico, Okin, and Bestelmeyer (2012).